Obama will also work the phones with Middle East leaders aboard Air Force One, just as he did throughout his four-day trip to Thailand, Burma and Cambodia, the last of which hosted a meeting of the Association of Southeast Asian Nations.

"The center of gravity for those (Middle East) discussions is in the region," said deputy national security adviser Ben Rhodes. "And the president is going to do a lot of work on the phone. He was on the phone until 2:30 in the morning last night; he left dinner and basically dealt with this for several hours."

State Department spokeswoman Victoria Nuland said Clinton "will emphasize the United States' interest in a peaceful outcome that protects and enhances Israel's security and regional stability; that can lead to improved conditions for the civilian residents of Gaza; and that can reopen the path to fulfill the aspirations of Palestinians and Israelis for two states living in peace and security."

As he flies back to Washington, Obama is also likely to monitor White House-congressional negotiations over a budget deal to reduce the growing federal debt.

Without a deal, Obama, congressional Republicans and congressional Democrats face the prospect of automatic tax hikes and budget cuts that could tip the economy back into a recession.